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The compaction process of calf thymus DNA by cationic liposomes formed by a 1:1 mixture of cationic lipid and zwitterionic lipid is studied using conductometry, cryo-TEM and fluorescence spectroscopy. The results show that when the charge ratio between the cationic liposome and DNA reaches 1, the liposome membranes fuse and cause the lead DNA to collapse onto condensed structures together with the liposomes.

The multimeric heteromer, which has mediated signaling, is reassembled and the monomers of the [M.sub.2] muscarinic receptor are purified from Sf9 cells and are incorporated into phospholipid vesicles, both alone and together with G proteins. The results have shown that monomers of the [M.sub.2] receptor can be assembled into tetramers with binding proteins that have resembled with those of the muscarinic receptor in myocardial preparations.

The effect of coenzyme [Q.sub.10] (Co[Q.sub.10]) incorporation on the characteristics of nanoliposomes, especially the hydrocarbon chain structures of membrane lipids, is investigated. The results have indicated that Co[Q.sub.10] might intercalate between lipid molecules and perturb the bilayer structure.

Two cationic phospholipid derivatives with asymmetric hydrocarbon chains were synthesized: ethyl esters of oleoyldecanoylethylphosphatidylcholine (C18:1/C10-EPC) and stearoyldecanoylethylphosphatidylcholine (C18:0/C10-EPC). The former was 50 times more effective as a DNA transfection agent (human umbilical artery endothelial cells) than the latter, despite their similar chemical structure and virtually identical lipoplex organization. A likely reason for the superior effectiveness of C18:1/C10-EPC relative to C18:0/C10-EPC (and to many other cationic lipoids) was suggested by the phases that evolved when these lipoids were mixed with negatively charged membrane lipid formulations. The saturated C18:0/C10-EPC remained lamellar in mixtures with biomembrane-mimicking lipid formulations [e.g., dioleoyl-phosphatidylcholine/dioleoyl-phosphatidylethanolamine/ dioleoyl-phosphatidylserine/cholesterol at 45:20:20:15 (wt/wt)]; in contrast, the unsaturated C18:1/C10-EPC exhibited a lamellar-nonlamellar phase transition in such mixtures, which took place at physiological temperatures, [approximately equal to] 37[degrees]C. As is well known, lipid vehicles exhibit maximum leakiness and contents release in the vicinity of phase transitions, especially those involving nonlamellar phase formation. Moreover, nonlamellar phase-forming compositions are frequently highly fusogenic. Indeed, FRET experiments showed that C18:1/C10-EPC exhibits lipid mixing with negatively charged membranes that is several times more extensive than that of C18:0/C10-EPC. Thus, C18:1/C10-EPC lipoplexes are likely to easily fuse with membranes, and, as a result of lipid mixing, the resultant aggregates should exhibit extensive phase coexistence and heterogeneity, thereby facilitating DNA release and leading to superior transfection efficiency. These results highlight the phase properties of the carrier lipid/cellular lipid mixtures as a decisive factor for transfection success and suggest a strategy for the rational design of superior cationic lipid carriers. lipofection | lipoplex | mesophase

A study was conducted to examine the structure and dynamics in binary sphingomyelin/phospholipid liposomes using two-dimensional infrared (2D-IR) spectroscopy. The diagonal component of the 2D-IR reveals a difference in the molecular dynamics while the presence of off-diagonal cross-peaks indicates the occurrence of intermolecular structural correlation.

The design of stable redox active liposomes is described where the organometallic electroactive pendent is covalently bound to the phospholipid headgroup through a phospholipase D (PLD)-catalyzed transphosphatidylation reaction between a choline-bearing phospholipid and a primary alcohol containing a ferrocene derivative. The functionalization of a liposome surface with the organometallic redox phospholipd has helped in studying membrane-bound electrochemical reactions, which are important for designing redox-sensitive liposome delivery systems.

A controllable shape transformation of polymer vesicles (polymersomes) constructed from block copolymers of which the hydrophobic part is a high-molecular-weight glassy segment is reported. The findings for the morphological diversity of giant liposomes and the physical robustness of polymersomes could be used as general strategy to realize unusual nanostructures in a predictable manner.

A structure-dynamics-based strategy is described for improving the antibiotic uptake and molecular simulations are used for describing the subtle balance of interactions governing ampicillin diffusion through the porin OmpF. The studies have shown the importance of microscopic interactions at the constriction region of the biological channel to control the antibiotic flux through it.

Solid-supported membrane-based electrophysiology with improved time resolution was employed to assess the electrogenic reactions accompanying downhill lactose/H(+) symport catalyzed by the lactose permease of Escherichia coli (LacY). The results from the analysis of rates of charge translocation generated by purified LacY reconstituted into proteoliposomes provide insight into the kinetic mechanism and electrogenic reaction triggered by sugar binding.

The oligomeric state of Grsp1 and Grp1 family proteins as well as the oligomeric state, stoichiometry, and specificity of Grsp1 complexes with Grp1, ARNO, and Cytohesin-1 were characterized to understand the homodimerization in vitro and heteromeric interaction mediated by the N-terminal heptad repeats in Grp1. The formation of Grsp1-Grp1 heterodimers were found to have no substantial influence on the binding of Grp1 to the headgroups of PtdIns(3,4,5)[P.sub.3] or PtdIns(4,5)[P.sub.2] and the partitioning with liposomes containing PtdIns(3,4,5)[P.sub.3], PtdIns(4,5)[P.sub.2], and/or phosphatidylserine.

Anionic liposomes are adsorbed onto the surface of spherical polymer particles bearing grafted linear cationic macromolecules. The size, shape, and encapsulation ability of the liposomes have remained unchanged upon adsorption, which have provided immobilized self-organizing containers that have potential applications in the biomedical field.

Alanine mutants are created for each residue in the transmembrane domain of phospholamban (PLB), the mutant are co-reconstituted with SERCA into proteoliposomes and kinetic simulations are performed on the calcium-dependent ATPase activity isotherms. The studies have shown that the PLB transmembrane mutants have a variable effect on the calcium affinity, maximal activity and cooperativity of SERCA.

A drop-in cholesterol-modified poly(acrylic acid) reagent followed by cross-linking with alkyne-functionalized diamine linker that allowed for the conjugation of azide-modified targeting ligands via click ligation was used to prepare modularly clickable polymer-caged nanobins (PCNs) from liposome templates. The PCNs obtained possessed pH-responsive characteristics that could be used to trigger the release of encapsulated doxorubicin (DXR) payload inside the liposomal core under mild acidic conditions.

The successful reconstitution of purified ABCC3 in proteoliposomes and ABCC3-dependent uptake of the anticancer drug methotrexate (MTX), as well as the physiological substrate leukotriene C4 (LTC4) is described. A specific transport in a cell-free environment and in the absence of other proteins which revealed positive allosteric cooperativity for ABCC3-mediated substrate translocation is also described.

The preparation and biophysical aspects of the formation of giant liposomes in solutions of physiologic ionic strength, such as phosphate buffered saline (PBS) or 150 mM KCl is discussed. The results showed that gentle hydration of hybrid films of agarose and lipids is a simple, rapid and reproducible procedure to generate giant liposomes of various lipid composition in solutions of physiologic ionic strength that does not require any specialized equipment.

The preparation and studies of a series of polybetaines ([PB.sub.n]) having cationic and anionic units covalently linked by short -[(C[H.sub.2]).sub.n]- spacer is reported. The results revealed that the length of the -[(C[H.sub.2]).sub.n]- spacer in betaine units have a significant effect on the ability of polybetaines to interact with anionic liposomes and to induce structural rearrangement within the liposomal membrane.

The functional reconstitution of [Man.sub.5]GlcN[Ac.sub.2]PP-dolichol (M5-DLO) flipping in large unilamellar proteoliposomes generated from Triton X-100-solubilized Saccharomyces cerevisiae endoplasmic reticulum (ER) membrane proteins. The studies have shown that the ER has at least two distinct flippase proteins and has provided a biochemical means of identifying the M5-DLO flippase.

The formation of highly magnetic and fluorescent giant vesicles inside different giant liposomes is discussed. The liposomes are shown to undergo extremely important deformations at extremely high ionic strengths.

The thermotropic, physical, and dynamical properties of large unilamellar liposomes formed from either 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) or 1,2-dimyristoyl-sn-glycero-3-[phospho-rac-glycerol] (DMPG) encapsulated in sol-gel matrixes are characterized. The results show that the electrostatic interactions between phospholipid polar heads and the porous surface of the host matrix play a vital role for the preservation of the structural integrity of encapsulated bilayer.

A novel system shown schematically in which intact lipid vesicles were assembled on a fluid-supported bilayer using oligonucleotide tethers is reported. The DNA-lipid conjugate described can be considered a reagent for tethering performed vesicle or proteoliposomes of arbitrary composition, content and origin to supported bilayer surfaces in a manner that encodes the identity of the vesicle or proteoliposome in DNA sequence.

The erythrocyte membrane is a composite structure consisting of a lipid bilayer tethered the spectrin-based membrane skeleton. The binding of spectrin and its constituent chains to mixed liposomes of phosphatidylserine (PS) and phosphatidylcholine (PC) depended on the proportion of PS.

The coarse-grained molecular dynamics simulations are used to study the spontaneous aggregation of dipalmitoylphosphatidylcholine lipids into small unilamella vesicles. The aggregation process occurs on a nanosecond time scale, with bicelles and cuplike vesicles formed at intermediate stages.

A study describes the construction of a novel conductive polymer/planar waveguide transducer that provides for highly sensitive detection of proton transport across a planar supported lipid bilayer (PSLB). The general and flexible nature of this architecture makes it adaptable to many different types of transmembrane transport chemistries, particularly light-activated systems.